As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETURNED TO BASE DUE TO A BURNING, CHEMICAL ODOR IN THE CABIN. THE MECHANIC PERFORMED A VISUAL INSPECTION, AND FOUND A BROKEN WIRE ON THE AC SYSTEM HI/LO PRESSURE SWITCH. CORRECTED THE DISCREPANCY AND HAD THE PILOT PERFORM A 30 MINUTE PENALTY RUN WITH NO DEFECTS NOTED. THE AIRCRAFT WAS RETURNED TO SERVICE AT THIS TIME.